CN106225696A - A kind of method of automatic measurement hub height - Google Patents

Abstract

The invention discloses a method for automatically measuring the height of a wheel hub. A CCD camera and an infrared camera collect an image respectively; on the color image collected by the CCD camera, Hough transform is used to extract the center position, radius and maximum contour circle of the wheel hub; Retrieve and extract the minimum non-zero depth value D1 within the contour circle on the depth image; obtain the hub bottom depth value D2 from the maximum contour circle of the depth image; calculate the hub height value H=D2‑D1. The invention also discloses a system for automatically measuring the height of the hub. The invention has high detection automation and high accuracy.

Description

A Method for Automatically Measuring Wheel Hub Height

technical field

The invention relates to computer vision technology, in particular to a method for automatically measuring the height of a wheel hub.

Background technique

Wheel hubs need to be designed in different shapes, diameters and heights according to the requirements of various automobile manufacturers. In the production process, each wheel hub needs to undergo X-ray flaw detection after being cast and formed, and then sent to different machining centers for shape processing. In order to choose the correct flaw detection and machining program, it is necessary to measure the hub height accurately.

At present, the detection of wheel height usually adopts adding a fixed-height grating sensor, but this only serves as a height threshold judgment function, that is, it gives a judgment result greater or less than the height. In fact, the height of the hub is uneven, and it is difficult to distinguish different types of hubs through a fixed threshold. The present invention adds a pair of infrared cameras on the plane of the camera that acquires the wheel spoke image, uses the depth image collected by the infrared camera to calculate the height of the feature point of the wheel hub, and finally extracts the height value of the wheel hub.

Contents of the invention

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for automatically measuring the hub height, which has a high degree of automation and high accuracy of detection.

Another object of the present invention is to provide a system for automatically measuring the height of a hub that realizes the above method.

The object of the present invention is achieved through the following technical solutions:

A method for automatically measuring the height of a wheel hub, comprising the steps of:

(1) Two horizontally arranged transmission chains are used to clamp the wheel hub; a camera assembly is arranged above the transmission chain; the camera assembly includes a CCD camera, an infrared emitter and an infrared camera;

(2) Establish a reference speckle library, including the following steps:

(2-1) At a distance of 5 meters from the infrared camera, place a plate with a rough surface for shooting planar speckle images as a reference plate;

(2-2) The infrared camera shoots a speckle image of the reference plate, takes the distance from the reference plate to the infrared camera as the position data, sets the captured speckle image as the reference speckle image at this position, and sets the reference The pattern and position data are stored in the reference speckle library at the same time;

(2-3) Move the reference plate to the direction of the infrared camera for a distance d, and the value of d is 0.5 ~ 1cm, and obtain the speckle pattern of the position and store the corresponding position data into the speckle library;

(2-4) Repeat step (2-3) until the reference plate moves to 0.5 meters away from the infrared camera to complete the establishment of the speckle library;

(3) Drive the two transmission chains to move in the same direction at the same speed, so that the hub moves in a straight line until it stops at the position of the CCD camera;

(4) The CCD camera and the infrared camera collect an image respectively;

(5) Each point on the speckle image collected by the infrared camera and each reference speckle image in the reference speckle library are sequentially performed cross-correlation calculations, and the calculation results correspond to the reference speckle images with peak values The distance is the actual distance from the point to the infrared camera, so as to obtain the depth image;

(6) Use Hough transform to extract the center position, radius and maximum contour circle of the wheel hub on the color image collected by the CCD camera;

(7) Retrieve and extract the minimum non-zero depth value D1 in the contour circle from the depth image;

(8) Obtain the hub bottom depth value D2 from the maximum contour circle of the depth image;

(9) Calculate the hub height value H=D2-D1.

Preferably, the rough-surfaced flat board is a wood board or a frosted glass board.

A system for automatically measuring the height of the hub for realizing the above-mentioned method for automatically measuring the height of the hub, including a PC, a camera assembly, and a transmission chain group;

The transmission chain group includes two horizontally arranged transmission chains, each of which is connected to a motor; the motor is electromechanically connected to the PC;

The camera assembly includes a CCD camera, an infrared emitter and an infrared camera, and is located directly above the conveyor chain group; the CCD camera, the infrared emitter and the infrared camera are respectively connected to a PC.

Preferably, the camera assembly is set at 1.7-2.7 meters directly above the conveyor chain group.

Preferably, the infrared emitter is located on the left side of the CCD camera, and the infrared camera is located on the right side of the CCD camera.

Preferably, the system of the method for automatically measuring the hub height further includes a user input device and a display device; the user input device and the display device are respectively connected to a PC.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention is easy to install, and the camera only needs to be installed at the position of the hub where the complete shooting radius is the largest;

(2) The present invention is far away from the wheel hub in space, and is convenient to be used in combination with other measuring equipment;

(3) The present invention has wide application scenarios and can measure the height of all types of hubs.

(4) The calculation speed of the algorithm of the present invention is fast, and fully meets the requirement of online detection.

(5) The present invention adopts an infrared light source, which is less affected by ambient light and is suitable for industrial detection.

Description of drawings

Fig. 1 is a schematic composition diagram of a system for automatically measuring hub height according to an embodiment of the present invention.

Fig. 2 is a flow chart of the method for automatically measuring the hub height of the embodiment of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example

As shown in FIG. 1 , the system for automatically measuring the height of a hub in this embodiment includes a PC 1 , a camera assembly 2 and a conveyor chain set 3 . The transmission chain group 3 includes two transmission chains, respectively connected to two transmission motors with identical performance. The motors in the camera assembly 2 and the transmission chain group 3 are electrically connected to the PC 1 respectively, and the hub 4 is clamped by the transmission chain group 3. When the two motors in the transmission chain group 3 rotate in reverse, the hub 4 is moved The chain group 3 is clamped for rotary motion, and when the motor rotates in the same direction, the hub 4 is clamped by the moving chain group 3 for linear motion. The camera assembly 2 comprises a CCD camera positioned in the middle, an infrared emitter positioned at the left side of the CCD camera and an infrared camera positioned at the right side of the CCD camera, and the camera assembly can select a Kinect somatosensory camera for use.

Loading in the PC machine 1 comprises loading in the PC machine and comprises the application program of measuring wheel hub height, and described PC machine 1 also comprises user input device and display device, used input device can be mouse and keyboard, used display device can be computer screen or LCD screen etc.

The camera assembly 2 transmits the hub color image collected by the CCD camera and the depth image collected by the infrared camera pair to the PC 1, and the PC 1 displays the hub height information after processing the images.

As shown in Figure 2, the method for automatically measuring the hub height of the present embodiment comprises the following steps:

(1) Two horizontally arranged transmission chains are used to clamp the wheel hub; a camera assembly is arranged above the transmission chain; the camera assembly includes a CCD camera, an infrared emitter and an infrared camera;

(2) Establish a reference speckle library, including the following steps:

(2-1) At a distance of 5 meters from the infrared camera, place a plate with a rough surface for shooting planar speckle images as a reference plate;

(2-2) The infrared camera shoots a speckle image of the reference plate, takes the distance from the reference plate to the infrared camera as the position data, sets the captured speckle image as the reference speckle image at this position, and sets the reference The pattern and position data are stored in the reference speckle library at the same time;

(2-3) Move the reference plate to the direction of the infrared camera for a distance d, and the value of d is 0.5 ~ 1cm, and obtain the speckle pattern of the position and store the corresponding position data into the speckle library;

(2-4) Repeat step (2-3) until the reference plate moves to 0.5 meters away from the infrared camera to complete the establishment of the speckle library;

(3) Drive the two transmission chains to move in the same direction at the same speed, so that the hub moves linearly to the CCD

The camera position stops;

(4) The CCD camera and the infrared camera collect an image respectively;

(5) Each point on the speckle image collected by the infrared camera and each reference speckle image in the reference speckle library are sequentially performed cross-correlation calculations, and the calculation results correspond to the reference speckle images with peak values The distance is the actual distance from the point to the infrared camera, so as to obtain the depth image;

(6) Use Hough transform to extract the center position, radius and maximum contour circle of the wheel hub on the color image collected by the CCD camera;

(7) Retrieve and extract the minimum non-zero depth value D1 in the contour circle from the depth image;

(8) Obtain the hub bottom depth value D2 from the maximum contour circle of the depth image;

(9) Calculate the hub height value H=D2-D1.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (6)

1. the method for an automatic measurement hub height, it is characterised in that comprise the following steps:

(1) two horizontally disposed transmission chain clamping wheel hubs are used；It is provided above CCD camera assembly at transmission chain；Described CCD camera assembly includes CCD camera, RF transmitter and infrared pick-up head；

(2) set up with reference to speckle picture library, comprise the steps:

(2-1) at distance infrared camera 5 meters, place one piece and be used for camera plane speckle pattern, shaggy flat board, as Reference plate；

(2-2) infrared camera shoots the speckle pattern of a width reference plate, by the distance of reference plate to infrared pick-up head is Position data, the reference speckle pattern that captured speckle pattern is set on this position, will with reference to speckle pattern and position data simultaneously It is stored in reference to speckle picture library；

(2-3) to infrared pick-up head direction, reference plate being moved a distance, d, d value is 0.5～1cm, obtains this position Speckle pattern and relevant position data be stored in speckle picture library；

(2-4) repeat step (2-3), until reference plate moves at 0.5 meter of infrared pick-up head, complete speckle picture library Set up；

(3) drive two transmission chains to move in the same direction with identical speed, make wheel hub move along a straight line to CCD camera position and stop Under；

(4) CCD camera and infrared pick-up head gather an image respectively；

(5) each point and each reference in described reference speckle picture library on the speckle image that infrared camera is collected Speckle pattern takes turns doing computing cross-correlation, and operation result occurs that the distance corresponding to reference speckle pattern of peak value is exactly that this point is to infrared The actual range of photographic head, thus draw depth image；

(6) Hough transformation is used to extract the home position of wheel hub, radius and maximum on the coloured image that CCD camera collects Profile circle；

(7) retrieve from depth image and extract the minimum non-zero depth value D1 in profile circle；

(8) at the largest contours circle of depth image, depth value D2 bottom wheel hub is obtained；

(9) hub height value H=D2-D1 is calculated.

The method of automatic measurement hub height the most according to claim 1, it is characterised in that described shaggy flat board For plank or focussing glass.

3. realize the method automatically measuring hub height described in any one of claim 1～2 measures hub height automatically System, it is characterised in that include PC, CCD camera assembly, transmission chain group；

Described transmission chain group includes two horizontally disposed transmission chains, and each transmission chain connects a motor respectively；Institute State motor to electrically connect with PC；

Described CCD camera assembly includes CCD camera, RF transmitter and infrared pick-up head, is just being located at transmission chain group Top；Described CCD camera, RF transmitter and infrared pick-up head are connected with PC respectively.

The system of automatic measurement hub height the most according to claim 3, it is characterised in that described CCD camera assembly is located at At directly over transmission chain group 1.7～2.7 meters.

5. according to the system automatically measuring hub height described in claim 3 or 4, it is characterised in that described infrared emitting Device is positioned at the CCD camera left side, and described infrared pick-up head is positioned on the right of CCD camera.

The system of automatic measurement hub height the most according to claim 3, it is characterised in that also include user input device And display device；Described user input device and display device are connected with PC respectively.